The Ruy Lopez is named after 16th-century Spanish bishop Ruy López de Segura. It is one of the most popular openings, with such a vast number of variations that in the Encyclopaedia of Chess Openings (ECO) all codes from C60 to C99 are assigned to them.

The opening is named after the 16th-century Spanish bishop Ruy López de Segura, who made a systematic study of this and other openings in the 150-page book on chess Libro del Ajedrez, written in 1561. Although it bears his name, this particular opening was included in the Göttingen manuscript, which dates from c. 1490. However, popular use of the Ruy Lopez opening did not develop until the mid-19th century, when Carl Jaenisch, a Russian theoretician, "rediscovered" its potential. The opening remains the most commonly used amongst the open games in master play; it has been adopted by almost all players during their careers, many of whom have played it with both colours. Due to the difficulty for Black in achieving equality,[2] a common nickname for the opening is "The Spanish Torture".

At the most basic level, White's third move attacks the knight which defends the e5-pawn from the attack by the f3 knight. White's apparent threat to win Black's e-pawn with 4.Bxc6 dxc6 5.Nxe5 is illusory—Black can respond with 5...Qd4, forking the knight and e4-pawn, which will win back the material with a good position. White's 3.Bb5 is still a good move; it develops a piece, prepares castling, and sets up a potential pin against Black's king. However, since White's third move carries no immediate threat, Black can respond in a wide variety of ways.

Traditionally, White's objective in playing the Ruy Lopez is to spoil Black's pawn structure; either way Black recaptures following the exchange on c6 will have negative features for him, though he thereby gains the bishop pair.[4] However, in modern practice, White does not always exchange bishop for knight on c6, preferring the retreat 4. Ba4 if chased by 3...a6.

The theory of the Ruy Lopez is the most extensively developed of all open games, with some lines having been analysed well beyond move thirty. At nearly every move there are many reasonable alternatives, and most have been deeply explored. It is convenient to divide the possibilities into two groups based on whether or not Black responds with (3...a6), which is named the Morphy Defence after Paul Morphy, although he was not the originator of the line.[5] The variations with Black moves other than 3...a6 are older and generally simpler, but the Morphy Defence lines are more commonly played.

By far the most commonly played third move for Black is the Morphy Defence, 3...a6, which "puts the question" to the white bishop. The main point of 3...a6 is that after the common retreat 4.Ba4, Black will have the possibility of breaking a future pin on his queen knight by playing ...b5. White must take some care not to fall into the Ruy Lopez, Noah's Ark Trap, in which Black traps White's king bishop on the b3-square with a ...a6, ...b5, and ...c4 pawn advance on the queenside.
Ercole del Rio, in his 1750 treatiseSopra il giuoco degli Scacchi, Osservazioni pratiche dell'anonimo Modenese (On the game of Chess, practical Observations by an anonymous Modenese), was the first author to mention 3...a6.[6] However, the move became popular after it was played by Paul Morphy, and it is named for him. Steinitz did not approve of the move; in 1889, he wrote, "on principle this ought to be disadvantageous as it drives the bishop where it wants to go". Steinitz's opinion did not prevail, however; today, 3...a6 is played in over 65 percent of all games beginning with the Ruy Lopez.[7]

After 3...a6, the most commonly played line is the Closed Defence, which goes 4.Ba4 Nf6 5.0-0 Be7, discussed in the two following sections. Alternatives to the Closed Defence described in this section are:

In the Exchange Variation, 4.Bxc6, (ECO C68–C69) White damages Black's pawn structure, giving him a ready-made long-term plan of playing d4 ...exd4 Qxd4, followed by exchanging all the pieces and winning the pure pawn ending. Max Euwe gives the pure pawn ending in this position (with all pieces except kings removed) as a win for White.[8] Black gains good compensation, however, in the form of the bishop pair, and the variation is not considered White's most ambitious, though former world champions Emanuel Lasker and Bobby Fischer employed it with success.

After 4.Bxc6, Black almost always responds 4...dxc6, although 4...bxc6 is playable. It is not usually played due to the reply 5.d4 exd4 6.Qxd4 and White is in control of the centre. After 4...dxc6, the obvious 5.Nxe5? is weak, since 5...Qd4! 6.Nf3 Qxe4+ 7.Qe2 Qxe2+ leaves White with no compensation for Black's bishop pair. There are two principal lines after 4.Bxc6 dxc6. In the late 19th and early 20th centuries, Lasker had great success with 5.d4 exd4 6.Qxd4 Qxd4 7.Nxd4. Since then, better defences for Black have been developed, and this line is considered to slightly favour Black. Jon Jacobs wrote in the July 2005 Chess Life (p. 21): "A database search (limited to games longer than 20 moves, both players FIDE 2300+) reveals the position after 7.Nxd4 was reached 20 times from 1985–2002. White's results were abysmal: +0−7=13."

The flexible 5.0-0 is sometimes called the Barendregt Variation, but it was Fischer who developed it into a serious weapon in the 1960s. Unlike 5.d4, it forces Black to defend his e-pawn, which he usually does with 5...f6, 5...Bg4, 5...Qd6 (the sharpest line, preparing queenside castling), 5...Qe7, 5...Qf6 or 5...Bd6. A rare but playable move is 5...Be6 (or 5...Be7), the idea being that if White plays 6.Nxe5, Black plays 6... Qd4, forking the knight and the e4-pawn. The move ...Qd4, regaining the pawn at e4, is usually impossible in these variations once White has castled, due to the open e-file.

White may also delay the exchange for a move or two: 4.Ba4 Nf6 5.Bxc6 or 5.0-0 Be7 6.Bxc6 (the Delayed Exchange Deferred), for example; at first glance this seems a waste of time, but Black having played ...Nf6 rules out defending the pawn with ...f6, and the bishop already being on e7 means that ...Bd6 would be a loss of tempo.

The Norwegian Variation (also called the Taimanov or Wing Variation) (ECO C70), 3...a6 4.Ba4 b5 5.Bb3 Na5 aims to eliminate the white bishop but is generally considered too time-consuming for Black. The usual continuation is 6.0-0 d6 7.d4 Nxb3, but the speculative sacrifice 6.Bxf7+?! Kxf7 7.Nxe5+, which drives the black king out, has been played. However, with accurate play, Black is supposed to be able to consolidate his extra piece.

This defence has been known since the 1880s and was reintroduced in 1901 by Carl Schlechter. In the 1950s, Mark Taimanov played it with some success, though it remained a sideline, as it has to this day. The Norwegian connection was first introduced by Svein Johannessen who played the line from 1957 and later strengthened when Simen Agdestein and some other Norwegian players adopted the variation. In 1995 Jonathan Tisdall published the article "Ruy Lopez. The Norwegian Variation" in New in Chess Yearbook 37.

The Graz Defence, Classical Defence Deferred, and Møller Defence combine 3...a6 with the active move ...Bc5.
For a century it was believed that it was safer for Black to place the bishop on e7, but it is much more active on c5.
White can gain time after playing d4 as the black bishop will have to move, but this does not always seem to be as important as was once thought.[9]

The Møller Defence, 3...a6 4.Ba4 Nf6 5.0-0 Bc5 was already an old line in 1903 when DaneJørgen Møller (1873–1944) analysed it in Tidsskrift för Schack. Alexander Alekhine played this for Black in the early portion of his career; despite his advocacy, it never achieved great popularity, and even he eventually came to consider it dubious.

The Graz Defence, 3...a6 4.Ba4 b5 5.Bb3 Bc5, was analysed by Alois Fink (b. 1910) in Österreichische Schachzeitung in 1956 and in Wiener Schach Nachrichten in 1979, although it did not become popular until the 1990s.

In the Modern Steinitz Defence (also called Neo-Steinitz Defence) (ECO C71–C76), Black interpolates 3...a6 4.Ba4 before playing 4...d6, which was frequently played by Alekhine, José Raúl Capablanca and Paul Keres. The possibility of breaking the pin with a timely ...b5 gives Black more latitude than in the Old Steinitz Defence; in particular, in the Old Steinitz, White can practically force Black to give up his strongpoint at e5, but in the Modern Steinitz, Black is able to maintain his centre. Most plausible White moves are playable here, including 5.c3, 5.c4, 5.Bxc6, 5.d4, and 5.0-0. The sharp Siesta Variation arises after 5.c3 f5, while a manoeuvring game results from the calmer 5.c3 Bd7 6.d4. The game is also sharp after 5.Bxc6+ bxc6 6.d4 (ECO C73) or 5.0-0 Bg4 6.h3 h5 (ECO C72). The older lines starting with 5.c4 and 5.d4 are not regarded as testing for Black, though the latter offers a tricky gambit. There are six ECO classifications for the Modern Steinitz. White's responses 5.d4, 5.Nc3, and 5.c4 are included in C71, while 5.0-0 is C72. The delayed exchange 5.Bxc6+ bxc6 6.d4 is C73. C74–C76 all begin with 5.c3. C74 covers 5...Nf6, but primarily focuses on 5...f5 6.exf5 Bxf5 with 7.d4 or 7.0-0. C75's main continuation is 5...Bd7 6.d4 Nge7, the Rubinstein Variation. C76 is characterised by the Black kingsidefianchetto 5...Bd7 6.d4 g6.

The Schliemann Defence Deferred, 3...a6 4.Ba4 f5, is rarely seen, with practically its only top-level appearance being in the 1974 Candidates Final, when Viktor Korchnoi adopted it versus Anatoly Karpov. It is considered inferior to the regular Schliemann, since White can answer effectively with 5.d4! exd4 6.e5.

The Mackenzie Variation 5.d4, is a sharp line followed normally by 5...exd4 6.0-0 and 6...Be7 instead of 6...Nxe4 because black will surely lose his knight. 7.Re1 follows, then black plays 7...b5. Some players prefer the simple 8.Bb3, while others go for the sharp 8.e5.

The Steinitz Defense Deferred (ECO C79) also called Russian Defence. With the move order 3...a6 4.Ba4 Nf6 5.0-0 d6, Black waits until White castles before playing ...d6. This can enable Black to avoid some lines in the Steinitz Defence Deferred in which White castles queenside although the position of the knight on f6 also precludes Black from supporting the centre with ...f7–f6. These nuances seem to have little importance today, as neither the Steinitz Defence Deferred nor the Russian Defence have been popular for many years.

Chigorin played the Russian Defence in the 1890s, and later it was adopted by Rubinstein and Alekhine. The last significant use of the Russian Defence was in the 1950s when it was played by some Russian masters.

The Arkhangelsk Defence (or Archangel Defence) (ECO C78) was popularized by Soviet players from the city of Arkhangelsk such as GM Vladimir Malaniuk. The variation begins 3...a6 4.Ba4 Nf6 5.0-0 b5 6.Bb3 Bb7. This line often leads to sharp positions in which Black wagers that the fianchettoed bishop's influence on the centre and kingside will offset Black's delay in castling. White has several options, including attempting to build an ideal pawn centre with c3 and d4, defending the e-pawn with Re1 or simply developing. The Arkhangelsk Defence is tactically justified by Black's ability to meet 7.Ng5 with 7...d5 8.exd5 Nd4! (not 8...Nxd5, when White gets the advantage with 9.Qh5 g6 10.Qf3).

The Modern Arkhangelsk Defence (or Modern Archangel Defence) (ECO C78) is a refinement of the regular Arkhangelsk Defense by incorporating ideas similar to the Møller Defence. Black normally does not fianchetto the Queen's bishop, which would transpose to regular Arkhangelsk setups, but plays ...Bg4 to increase the pressure against White's pawn centre. White's main continuation is 7.a4 after which Black responds with the typical move 7...Rb8 reaching the starting point of this highly complex variation. Another line is the more traditional 7.c3 d6 8.d4 and after 8...Bb6 Black's position is fine. 8...exd4 occurred in Loewenthal vs Morphy, London 1859 [10]) which seems to be the first time this variation was ever played.

In the Open Defence, 3...a6 4.Ba4 Nf6 5.0-0 Nxe4, Black tries to make use of the time White will take to regain the pawn to gain a foothold in the centre, with play usually continuing 6.d4 b5 7.Bb3 d5 (but not 7...exd4? 8.Re1 d5 9.Nc3!, Bobby Fischer vs Petar Trifunovic, Bled 1961 [12]) 8.dxe5 Be6. Here 8.Nxe5, once adopted by Fischer, is much less often seen, and Black should equalise after the accurate 8...Nxe5 9.dxe5 c6, which avoids prematurely committing the light-squared bishop and solidly defends d5, often a problem in the Open. The Riga Variation, 6...exd4, is considered inferior; the main line runs 7.Re1 d5 8.Nxd4 Bd6! 9.Nxc6 Bxh2+! 10.Kh1! (10.Kxh2 Qh4+ 11.Kg1 Qxf2+ draws by perpetual check.) Qh4 11.Rxe4+! dxe4 12.Qd8+! Qxd8 13.Nxd8+ Kxd8 14.Kxh2 Be6 (14...f5?? 15.Bg5#!) and now the endgame is considered to favour White after 15.Be3 or Nd2 (but not 15.Nc3 c5!, playing to trap the bishop). A famous example of this line is the game José Raúl Capablanca vs Edward Lasker, New York 1915.[13]

White has a variety of options at move nine, including 9.c3, 9.Be3, 9.Qe2 and 9.Nbd2.

The classical line starts with 9.c3 when Black may choose from 9...Na5, 9...Be7 (the main line), and the aggressive 9...Bc5.

After 9.c3 Bc5 10.Nbd2 0-0 11.Bc2, Black must meet the attack on e4, with the following possibilities from which to choose: 11...f5, 11...Bf5, both of which aim to maintain the strongpoint on e4, or the forcing line 11...Nxf2, introduced by the English amateur Vernon Dilworth.

Today, 9.Be3 Be7 10.c3 is often used to transpose into the main line, 9.c3, while obviating the option of the Dilworth.

An old continuation is 11...f5, when after 12.Nb3 Ba7 13.Nfd4 Nxd4 14.Nxd4 Bxd4 White can gain some advantage with Bogoljubov's 15.Qxd4. Instead, the very sharp La Grande Variante continues 15.cxd4 f4 16.f3 Ng3 17.hxg3 fxg3 18.Qd3 Bf5 19.Qxf5 Rxf5 20.Bxf5 Qh4 21.Bh3 Qxd4+ 22.Kh1 Qxe5, with unclear consequences. Perhaps the most famous game in this variation is Smyslov–Reshevsky, 1945 USSR–USA Radio Match. An analysis of the line had just been published in a Russian chess magazine, and Smyslov was able to follow it to quickly obtain a winning position. Reshevsky had not seen the analysis and he struggled in vain to solve the position over the board with his chess clock running. The Dilworth Variation (or Attack), 11...Nxf2 12.Rxf2 f6 13.exf6 Bxf2+ 14.Kxf2 Qxf6 has scored well for Black, with many traps for the ill-prepared White player. The main line leads to unbalanced endgames which are difficult to play for both sides, though with a strong drawing tendency. Yusupov is one of the few grandmasters to often adopt the Dilworth.

In the Howell Attack (ECO C81), 9.Qe2, White aims for play against d5 after Rd1. The game usually continues 9...Be7 10.Rd1 followed by 10...Nc5 or 10...0-0. Keres played this line several times in the late 1940s, and it is sometimes named after him.

Karpov's move, 9.Nbd2, limits Black's options. In the 1978 Karpov–KorchnoiWorld Chess Championship match, following 9.Nbd2 Nc5 10.c3 d4 (10...Be7 is an old move that remains popular) Karpov introduced the surprising 11.Ng5!?, a move suggested by his trainer, Igor Zaitsev. If Black takes the knight with 11...Qxg5 White regains the material with 12.Qf3. This variation played a decisive role in a later World Championship match, Kasparov–Anand 1995, when Anand was unable to successfully defend as Black.

In the main line, White normally retreats his bishop with 4.Ba4, when the usual continuation is 4...Nf6 5.0-0 Be7.
Black now threatens to win a pawn with 6...b5 followed by 7...Nxe4, so White must respond.
Usually White defends the e-pawn with 6.Re1 which, in turn, threatens Black with the loss of a pawn after 7.Bxc6 and 8.Nxe5.
Black most commonly averts this threat by driving away the white bishop with 6...b5 7.Bb3, although it is also possible to defend the pawn with 6...d6.

After 4...Nf6 5.0-0 Be7, the most frequently seen continuation is 6.Re1 b5 7.Bb3 d6 8.c3 0-0, discussed in the next section.
Examined in this section are the alternatives to the main line:

The Delayed Exchange Variation Deferred (or Exchange Variation Doubly Deferred) (ECO C85), 6.Bxc6, loses a tempo compared to the Exchange Variation, though in compensation, the black knight on f6 and bishop on e7 are awkwardly placed. The knight on f6 prevents Black from supporting the e-pawn with ...f7–f6, and the bishop is somewhat passively posted on e7.

In the Worrall Attack (ECO C86), White substitutes 6.Qe2 for 6.Re1. The idea is that the queen will support the e-pawn, leaving the rook free to move to d1 to support the advance of the d-pawn, although there is not always time for this. Play normally continues 6...b5 7.Bb3 followed by 7...0-0 8.c3 and 8...d5 or 8...d6.

By playing 6.d3 [14] White steers clear of the Marshall Attack and any of the Anti-Marshall lines. White threatens 7.Bxc6 winning the e5-pawn leaving Black a choice of either 6...d6 or 6...b5. After 6...d6 the e5-pawn is firmly defended and Black threatens to trade off White's Ruy Lopez bishop with 7...b5 and 8...Na5. White normally continues with 7.c3 and after 8...0-0 White can choose between 9.Nbd2 or 9 Re1. Black can also play 6...b5 and after 7.Bb3 d6 (7...0-0 is a viable alternative) White has to deal with the threat of 8...Na5 by playing 8.a3 (8.c3 or 8 a4 are perfectly playable as well) and after 8...0-0 (the immediate 8...Na5 is also feasible) 9.Nc3 we have reached a modern tabiya of the Ruy Lopez. This position was first reached in a high-level encounter between Viswanathan Anand and Michael Adams, Grenke Chess Classic 2013.[15] 6.d3 has gained wide popularity among the top players and has almost supplanted the Ruy Lopez main line with 6.Re1.

In the Averbakh Variation (C87), named for Yuri Averbakh, Black defends the threatened e-pawn with 6...d6 instead of driving away the white bishop with the more common 6...b5. This defence shares some similarities with the Modern Steinitz and Russian Defences as Black avoids the ...b5 advance that weakens the queenside. White can reply with either 7.Bxc6 bxc6 8.d4 or 7.c3 Bg4 (it is too late for Black to transpose into the more usual lines of the Closed Defence, because 7...b5 would allow 8.Bc2, saving White a tempo over the two-move sequence Bb3–c2 found in other variations). The pin temporarily prevents White from playing d2–d4. In response, White can either force d4 with 8.h3 Bh5 9.Bxc6 bxc6 10.d4, or postpone d4 for the time being and play 8.d3 followed by manoeuvering the queen knight to the kingside with Nbd2–f1–g3.

After 6.Re1 b5 7.Bb3, Black often plays 7...0-0. Here White can play 8.c3, but he has other moves. Alternatives are 8.a4, 8.h3, 8.d4, and 8.d3, which are often called "anti-Marshall" moves. White can also play 8.Nc3 with the idea of playing 9.Nd5 later.

In the case White does play 8.c3, Black can and often does play 8...d6, which is just the main line in another order. But he can also play 8...d5 for the Marshall Attack.

Marshall Attack after 11...c6, the most common move in modern play.[17] In 1918 Marshall played 11...Nf6.[18]

One of Black's more aggressive alternatives is the Marshall Attack: after 3...a6 4.Ba4 Nf6 5.0-0 Be7 6.Re1 b5 7.Bb3 0-0 8.c3 Black plays the gambit 8...d5, sacrificing a pawn. The main line begins with 9.exd5 Nxd5 (9...e4?!, the Herman Steiner variation, is considered weaker) 10.Nxe5 Nxe5 11.Rxe5 c6 (Marshall's original moves, 11...Nf6, and 11...Bb7 are considered inferior, but have also yielded good results at top levels of play for Black. GM Joel Benjamin suggests that 11...Bb7 is inferior due to 12.Qf3). The resulting position is shown in the diagram. To the casual observer it might seem that Black has been careless and lost a pawn; however the sacrifice has also stripped White's kingside of its defenders, given Black a lead in development, and rendered White's 8.c3 irrelevant. Since Black's compensation is based on positional rather than tactical considerations, it is difficult or perhaps impossible to find a refutation. Black generally goes all-in with a massive kingside attack, which has been analyzed to great depth (sometimes beyond move 30) with no definite conclusion as to the Marshall's soundness. The Marshall Attack is a very sharp opening system in which a great amount of theoretical knowledge is vital, and many White players, including Garry Kasparov, avoid it by playing one of the anti-Marshall systems, 8.d4, 8.a4 or 8.h3 instead of 8.c3.[17][not in citation given]

This gambit became famous when Frank James Marshall used it as a prepared variation against José Raúl Capablanca in 1918; nevertheless Capablanca found a way through the complications and won.[18] It is often said that Marshall had kept this gambit a secret for use against Capablanca since his defeat in their 1909 match.[19] The most common counterclaim is that Marshall had used a similar approach in 1917 against Walter Frere,[20] However Edward Winter found no clear evidence of the date for Frere vs Marshall; several games between 1910 and 1918 where Marshall passed up opportunities to use the Marshall Attack against Capablanca; and an 1893 game that used the same line as in Frere vs Marshall.[21]

The main lines of the Closed Ruy Lopez continue 6.Re1 b5 7.Bb3 d6 8.c3 0-0. White can now play 9.d3 or 9.d4, but by far the most common move is 9.h3 which prepares d4 while preventing the awkward pin ...Bg4. This can be considered the main line of the opening as a whole and thousands of top-level games have reached this position. White aims to play d4 followed by Nbd2–f1–g3, which would firmly support e4 with the bishops on open diagonals and both knights threatening Black's kingside. Black will try to counter this knight manoeuver by expanding on the queenside, taking action in the centre, or putting pressure on e4.

The Pilnik Variation, named for Herman Pilnik, is also known as the Teichmann Variation from the game Teichmann–Schlechter, Carlsbad 1911. White plays 9.d3 intending to later advance to d4 under favourable circumstances. Although d2–d3–d4 appears to lose a tempo compared to d2–d4, White may be able to omit h3 regaining the tempo, especially if Black plays ...Bb7.

White usually plays 9.h3 instead of 9.d4 (the Yates Variation) because after 9.d4 Bg4 (the Bogoljubow Variation), the pin of the white king knight is troublesome. The variation takes its name from the game Capablanca–Bogoljubow, London 1922.[23]

The Chigorin Variation was refined by Mikhail Chigorin around the turn of the 20th century and became the primary Black defence to the Ruy Lopez for more than fifty years. With 9...Na5 Black chases the white bishop from the a2–g8 diagonal and frees the c-pawn for queenside expansion. After 10.Bc2 c5 11.d4 the classical Black follow up is 11...Qc7, reinforcing e5 and placing the queen on the c-file which may later become open after ...cxd4. Other Black moves in this position are 11...Bb7 and 11...Nd7; the latter was adopted by Keres a few times in the 1960s. The Chigorin Variation has declined in popularity because Black must spend some time bringing his offside knight on a5 back into the game.

The Chigorin is divided into four ECO classifications. In C96, Black or White deviate after 10.Bc2, and do not reach the classical main line position 10...c5 11.d4 Qc7. In C97, White proceeds from the diagram with 12.a4, 12.d5, 12.b4, or the main line 12.Nbd2 when Black responds with ...Be6, ...Rd8, ...Re8, ...Bb7 or ...Bd7. The C98 classification covers 12.Nbd2 Nc6, while C99 covers 12.Nbd2 cxd4 13.cxd4.

The Breyer Variation was recommended by Gyula Breyer as early as 1911,[24] but there are no known game records in which Breyer employed this line. The Breyer Variation did not become popular until the 1960s when it was adopted by Boris Spassky and others. In particular, Spassky's back to back wins over Mikhail Tal at Tbilisi in 1965 did much to enhance its reputation, and Spassky has a career-plus score with the Breyer. The variation is the choice of many top level players today as White has had trouble proving an advantage against it.

With 9...Nb8 Black frees the c-pawn and intends to route the knight to d7 where it supports e5. If White fortifies the centre with 10.d3 the opening is classified ECO code C94. The more common continuation, 10.d4, is ECO C95. The main line continues 10.d4 Nbd7 11.Nbd2 Bb7 12.Bc2 Re8 13.Nf1 Bf8. Black is threatening to win the e4-pawn via ...exd4 uncovering an attack on the pawn, so White plays 14.Ng3. Black generally plays 14...g6 to stop White's knight from going to f5. White then usually tries to attack the Black queenside via 15.a4. Black seeks counterplay in the centre via 15...c5. White can attack either the kingside or the queenside. This forces resolution of the centre via 16.d5. Black can exploit the weak squares on the queenside via 16...c4. White will try to attack on the kingside via 17.Bg5, moving his forces to the kingside. Black will kick the bishop with 17...h6. The logical retreat is 18.Be3, which is met by 18...Nc5. White plays 19.Qd2, forcing 19...h5. The point of this manoeuver was to weaken Black's kingside.

The Zaitsev Variation (also called the Flohr–Zaitsev Variation) was advocated by Igor Zaitsev, who was one of Karpov's trainers for many years. A Karpov favourite, the Zaitsev remains one of the most important variations of the Ruy Lopez. With 9...Bb7 Black prepares to put more pressure on e4 after 10.d4 Re8 11.Nbd2 Bf8 when play can become very sharp and tactical. One drawback of this line is that White can force Black to choose a different defence or allow a draw by repetition of position with 11.Ng5 Rf8 12.Nf3.

Karpov tried 9...Nd7 several times in the 1990 World Championship match, but Kasparov achieved a significant advantage against it in the 18th game. It is solid but slightly passive. Confusingly 9...Nd7 is also called the Chigorin Variation so there are two variations of the Ruy Lopez with that name, but 9...Na5 is the move more commonly associated with Chigorin. This defense is also known as the Keres Variation, after Paul Keres.

The Kholmov Variation, 9...Be6, was popular in the 1980s but is now rarely played. The main line runs 10.d4 Bxb3 11.axb3 (11.Qxb3 is another option) exd4 12.cxd4 d5 13.e5 Ne4 14.Nc3 f5 15.exf6 Bxf6 16.Nxe4 dxe4 17.Rxe4 Qd5 18.Rg4, when it has been shown that White's extra pawn is more valuable than Black's more active and harmonised pieces.

The Smyslov Variation (ECO C93) is a plan similar to that of the Zaitsev Variation. With 9...h6 Black prepares to play 10...Re8 and 11...Bf8 without fear of 10.Ng5. The loss of a tempo with 9...h6 gives White enough time to complete the Nbd2–f1–g3 manoeuver, and the pawn move can also weaken Black's kingside. The Zaitsev can be considered to be an improved Smyslov in which Black tries to save a tempo by omitting ...h6.

The Cozio Defence (part of ECO C60), 3...Nge7, is distinctly old-fashioned and the least popular of the defences at Black's third move. Although Bent Larsen used it occasionally with success, it remains one of the least explored variations of the Ruy Lopez.

The Smyslov Defence, Fianchetto Defence, Barnes Defence, or Pillsbury Defence (part of ECO C60), 3...g6, is a quiet positional system played occasionally by Vasily Smyslov and Boris Spassky, becoming popular in the 1980s when it was shown that 4.c3 a6! gives Black a good game.

It was later discovered that 4.d4 exd4 5.Bg5 gives White the advantage, and as such the variation is rarely played today. An interesting gambit line 4.d4 exd4 5.c3 has also been recommended by Alexander Khalifman, although some of the resulting positions have yet to be extensively tested.

The Steinitz Defence (also called the Old Steinitz Defence) (ECO C62), 3...d6, is solid but passive and cramped.
Although the favourite of the first world championWilhelm Steinitz, and often played by world champions and expert defensive players Emanuel Lasker, José Capablanca, and occasionally by Vasily Smyslov, it largely fell into disuse after World War I, as its inherent passivity spurred a search for more active means of defending the Spanish. White can force Black to concede the strongpoint at e5 (see Tarrash Trap), a significant but not fatal concession. 4.d4 Bd7 breaks the pin. 5.0-0 Nf6 attacks the e-pawn 6. Nc3 Be7 finishes development for black. After 7.Re17...exd4 concedes the centre to White but is still a playable game for Black, whereas 7...0-0?! can lead to the Tarrasch trap.

The modern variant of this defence (3...a6 4.Ba4 d6) offers Black a freer position and is more popular.

The Schliemann 's Defence or Schliemann–Jaenisch Gambit (ECO C63), 3...f5!?, is a sharp line in which Black plays for a kingside attack, frequently sacrificing one or two pawns. Considered by many to be somewhat dubious, it is occasionally used in top-level play as a surprise weapon. This variation was originated by Carl Jaenisch in 1847 and is sometimes named after him. Although later named for German lawyer Adolf Karl Wilhelm Schliemann (1817–1872), the line Schliemann actually played in the 1860s was a gambit variation of the Cordel Defence (3...Bc5 4.c3 f5). The most common responses for White to 3...f5!? are 4.d3 or 4.Nc3, with play after 4.Nc3 fxe4 5.Nxe4 going 5...d5, with great complications to follow, or 5...Nf6, which generally leads to quieter play.

The Classical Defence or Cordel Defence (ECO C64), 3...Bc5, is possibly the oldest defence to the Ruy Lopez, and has been played occasionally by former world championBoris Spassky and Boris Gulko. White's most common reply is 4.c3, when Black may choose to play 4...f5, the Cordel Gambit, leading to sharp play, after which 5.d4 is considered the strongest reply. More solid for Black is instead, 4...Nf6, when 5.0-0 0-0 6.d4 Bb6 leads to the Benelux Variation. White's principal alternative to 4.c3 is 4.0-0, when Black can transpose to the Classical Berlin with 4...Nf6 or play 4...Nd4 which isn't so bad for Black.

An alternative for White is the fork trick 4. Nxe5. Few games have been played with this line, but there is no clear refutation for Black. The name derives from White's play if Black captures the knight: 4...Nxe5 5. d4.

Since Black's third move does not threaten to win the e-pawn—if Black captures it, White will win back the pawn on e5[31]—White usually castles. After 4.0-0, Black can play either the solid 4...Nxe4 (the Open Variation) or the more combative 4...Bc5 (the Berlin Classical Variation). After 4...Nxe4 5.d4 (5.Re1 Nd6 6.Nxe5 is also reasonable) Nd6 (5...Be7 is the Rio de Janeiro Variation) 6.Bxc6 dxc6 7.dxe5 Nf5 8.Qxd8+ Kxd8 (l'Hermet Variation), White is considered to have a small advantage in light of his somewhat better pawn structure and Black's awkwardly placed king. Black, by way of compensation, possesses the bishop pair and his position has no weaknesses, so it is difficult for White to exploit his structural superiority without opening the game for Black's bishops; all four of the games in the Kasparov–Kramnik match in which this line was employed ended in draws. An alternative for Black, though seldom seen since the 1890s, is 6...bxc6 7.dxe5 Nb7, although White keeps an advantage despite Black's two bishops, as it is difficult for him to gain active counterplay.

Another possible try for White is 4.d3. This is "Steinitz's move, with which he scored many spectacular successes during his long reign as World Champion".[32] The main replies for Black are 4...d6 and 4...Bc5. In both cases, White commonly plays 5. c3. An uncommon and dubious reply is 4...Ne7, which tries to set up the Mortimer Trap.

^As of 2016-11-23, Chess-DB.com [1] reports that 243,757 out of 355,830 games in its database beginning with the Ruy Lopez, continued with 3...a6, i.e. a percentage of approx. 68.5%. Similarly, 365Chess.com [2] reports a 69.3% percentage (100,540 out of 145,061 games) and ChessBase.com [3] (requires free registration) reports a 74.3% percentage (63,183 out of 85,022 games).

^Nandanan, Hari Hara (2 October 2011). "Carlsen stops Ivanchuk, Anand held". The Times of India. Bennett, Coleman & Co. Ltd. Retrieved 29 May 2015. Anand carefully employed the anti-Marshall against Aronian, an acknowledged expert in the Marshall. The Indian waited for things to unfold rather than forcing the pace in his characteristic way but after waiting for sometime on move 21 he deviated from the known track. Though he seemed to have got something out of the opening, the World champion did not have anything special.